Method for connecting piezoelectric element and cable substrate, piezoelectric element having cable substrate, and inkjet head including piezoelectric element with cable substrate

Abstract

A connection method disclosed herein includes softening a resin film of a thermosetting resin by heating an element electrode of a piezoelectric body and a substrate electrode of a flexible cable to be connected to the piezoelectric body with the element electrode and the substrate electrode being pressed into contact with each other via the resin film; partially pushing out the molten resin film from an opposing position of the element electrode and the substrate electrode so as to bring a solder layer provided on the substrate electrode into contact with the element electrode; curing the resin film and melting solder in the solder layer by further raising a heating temperature; discharging excess solder in a direction defined by the cured resin film; and then solidifying the solder in the solder layer so as to solder the element electrode and the substrate electrode together.

What is claimed is: 
     
       1. A method for connecting a piezoelectric element and a cable substrate, the method comprising:
 softening a resin film by pressing and heating the resin film between a plurality of element electrodes located at the piezoelectric element and a plurality of substrate electrodes located on the cable substrate with the resin film and solder being sandwiched between the plurality of element electrodes and the plurality of substrate electrodes, each of the plurality of substrate electrodes having a shape of a line; 
 curing the resin film by further heating the resin film that has been softened; 
 melting the solder, and pushing out along the line a portion of the solder located at an opposing position by the pressing, the opposing position being a position where the plurality of element electrodes and the plurality of substrate electrodes are opposed to each other; and 
 solidifying the solder between the plurality of substrate electrodes and the plurality of element electrodes. 
 
     
     
       2. The method according to  claim 1 ,
 wherein the piezoelectric element has a cut-out portion that is in contact with the plurality of element electrodes and defines a gap between the piezoelectric element and the cable substrate, the gap being greater than a distance between the plurality of substrate electrodes and the plurality of element electrodes, and 
 the portion of the solder that has been pushed out along the line is solidified in the cut-out portion. 
 
     
     
       3. The method according to  claim 2 ,
 wherein the plurality of substrate electrodes extend from the opposing position to a position where the plurality of substrate electrodes are opposed to the cut-out portion. 
 
     
     
       4. The method according to  claim 2 ,
 wherein the resin film extends from the opposing position to a position where the resin film is opposed to the cut-out portion. 
 
     
     
       5. The method according to  claim 1 ,
 wherein the piezoelectric element includes a plurality of piezoelectric bodies that are adjacent to each other via grooves, and 
 the plurality of element electrodes are located respectively in the plurality of piezoelectric bodies.